tree ffb47af052710469fb5b930e8e5327022fbe38bd
parent 8d476cd6793c73cc6ac15a93a3d003733089eb2a
author Erik Pilkington <erik.pilkington@gmail.com> 1528144703 +0000
committer Erik Pilkington <erik.pilkington@gmail.com> 1528144703 +0000

Fix a strict aliasing violation in map and unordered_map.

These containers type-punned between pair<K, V> and pair<const K, V> as an
optimization. This commit instead provides access to the pair via a pair of
references that assign through to the underlying object. It's still undefined to
mutate a const object, but clang doesn't optimize on this for data members, so
this should be safe.

Differential revision: https://reviews.llvm.org/D47607

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@333948 91177308-0d34-0410-b5e6-96231b3b80d8